sched: Add userspace interface to set PF_WAKE_UP_IDLE

sched_prefer_idle flag controls whether tasks can be woken to any
available idle cpu. It may be desirable to set sched_prefer_idle to 0
so that most tasks wake up to non-idle cpus under mostly_idle
threshold and have specialized tasks override this behavior through
other means. PF_WAKE_UP_IDLE flag per task provides exactly that. It
lets tasks with PF_WAKE_UP_IDLE flag set be woken up to any available
idle cpu independent of sched_prefer_idle flag setting. Currently
only kernel-space API exists to set PF_WAKE_UP_IDLE flag for a task.
This patch adds a user-space API (in /proc filesystem) to set
PF_WAKE_UP_IDLE flag for a given task. /proc/[pid]/sched_wake_up_idle
file can be written to set or clear PF_WAKE_UP_IDLE flag for a given
task.

Change-Id: I13a37e740195e503f457ebe291d54e83b230fbeb
Signed-off-by: Srivatsa Vaddagiri <vatsa@codeaurora.org>
[rameezmustafa@codeaurora.org: Port to msm-3.18]
Signed-off-by: Syed Rameez Mustafa <rameezmustafa@codeaurora.org>
[joonwoop@codeaurora.org: fixed minor conflict in kernel/sched/fair.c]
Signed-off-by: Joonwoo Park <joonwoop@codeaurora.org>

1 files changed, 72 insertions, 2 deletions

diff --git a/fs/proc/base.c b/fs/proc/base.c
index 7737df006b0d..faee999d19ff 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -1408,11 +1408,78 @@ static const struct file_operations proc_pid_sched_operations = {
 
 #endif
 
-#ifdef CONFIG_SCHED_HMP
-
 /*
  * Print out various scheduling related per-task fields:
  */
+
+#ifdef CONFIG_SMP
+
+static int sched_wake_up_idle_show(struct seq_file *m, void *v)
+{
+	struct inode *inode = m->private;
+	struct task_struct *p;
+
+	p = get_proc_task(inode);
+	if (!p)
+		return -ESRCH;
+
+	seq_printf(m, "%d\n", sched_get_wake_up_idle(p));
+
+	put_task_struct(p);
+
+	return 0;
+}
+
+static ssize_t
+sched_wake_up_idle_write(struct file *file, const char __user *buf,
+	    size_t count, loff_t *offset)
+{
+	struct inode *inode = file_inode(file);
+	struct task_struct *p;
+	char buffer[PROC_NUMBUF];
+	int wake_up_idle, err;
+
+	memset(buffer, 0, sizeof(buffer));
+	if (count > sizeof(buffer) - 1)
+		count = sizeof(buffer) - 1;
+	if (copy_from_user(buffer, buf, count)) {
+		err = -EFAULT;
+		goto out;
+	}
+
+	err = kstrtoint(strstrip(buffer), 0, &wake_up_idle);
+	if (err)
+		goto out;
+
+	p = get_proc_task(inode);
+	if (!p)
+		return -ESRCH;
+
+	err = sched_set_wake_up_idle(p, wake_up_idle);
+
+	put_task_struct(p);
+
+out:
+	return err < 0 ? err : count;
+}
+
+static int sched_wake_up_idle_open(struct inode *inode, struct file *filp)
+{
+	return single_open(filp, sched_wake_up_idle_show, inode);
+}
+
+static const struct file_operations proc_pid_sched_wake_up_idle_operations = {
+	.open		= sched_wake_up_idle_open,
+	.read		= seq_read,
+	.write		= sched_wake_up_idle_write,
+	.llseek		= seq_lseek,
+	.release	= single_release,
+};
+
+#endif	/* CONFIG_SMP */
+
+#ifdef CONFIG_SCHED_HMP
+
 static int sched_init_task_load_show(struct seq_file *m, void *v)
 {
 	struct inode *inode = m->private;
@@ -2811,6 +2878,9 @@ static const struct pid_entry tgid_base_stuff[] = {
 	ONE("status",     S_IRUGO, proc_pid_status),
 	ONE("personality", S_IRUSR, proc_pid_personality),
 	ONE("limits",	  S_IRUGO, proc_pid_limits),
+#ifdef CONFIG_SMP
+	REG("sched_wake_up_idle",      S_IRUGO|S_IWUSR, proc_pid_sched_wake_up_idle_operations),
+#endif
 #ifdef CONFIG_SCHED_HMP
 	REG("sched_init_task_load",      S_IRUGO|S_IWUSR, proc_pid_sched_init_task_load_operations),
 #endif